With the increasing support from governments worldwide for the development of new energy vehicles, the production and sales of electric vehicles have grown rapidly, leading to accelerated industrialization. However, thermal runaway remains a significant safety concern for electric vehicles, particularly concerning lithium-ion batteries used as their power source. Overcharging can cause high temperatures, resulting in fires and explosions. To address this issue, aerogel insulation materials have emerged as an effective solution to enhance the safety of electric vehicles.
Benefits of Aerogel Insulation Materials:
Aerogels possess several key advantages, including low thermal conductivity, excellent insulation performance, and non-combustibility. Compared to traditional insulation materials, aerogels offer the same level of insulation effectiveness with only 1/5 to 1/3 of the thickness. This space-saving attribute is especially crucial for power batteries, allowing for improved thermal control and management, enhanced performance, and more stable temperatures. Aerogel insulation materials act as insulation and fire-resistant barriers, providing users and passengers with additional time to evacuate and extinguish fires.
Applications of Aerogel Insulation Materials in Electric Vehicles:
Aerogel insulation materials find application in various aspects of new energy vehicles, including insulation and flame retardancy between battery cells, insulation and shock absorption between modules and casings, external cold protection layers for battery boxes, and high-temperature insulation layers. Let's take the example of aerogel insulation pads used for power batteries and analyze their main performance indicators.
Performance Requirements for Aerogel Insulation Pads:
According to the T/CSTM 00193-2020 Group Standard for Aerogel Insulation Pads Used in Lithium-ion Power Batteries, the main performance requirements are as follows:
1. Mass deviation rate: Should not exceed 15%.
2. Thermal insulation performance: The shrinkage of the sample's length and width dimensions before and after the test should not exceed 3%. The temperature on the cold side of the sample should not exceed 180°C within 5 minutes of the test.
3. Vertical burning: Should meet the V0 level requirements specified in GB/T 2408.
4. Compression ratio: Should not be less than 35% under a pressure of 2 MPa.
5. Tensile strength: Should be not less than 500 kPa in both the length and width directions.
6. Insulation performance: Surface thermal resistance should be greater than 500 MΩ, and the leakage current should be less than 1 mA.
7. Restricted substances: Should comply with the requirements of Directive 2011/65/EU.
8. Aging resistance: After aging, the tensile strength attenuation rate should not exceed 30%, and the length and width dimensions' variation rate should be less than 1%. The thermal insulation performance should meet the requirements specified in the table.
Comparison with Traditional Insulation Materials:
Commonly used insulation materials for power batteries include foam, plastic foam, ultra-fine glass wool, high-silica cotton, vacuum insulation panels, and silica aerogel. Compared to traditional insulation pads, aerogel insulation pads offer flame retardancy, high-temperature resistance, low thermal conductivity, no toxic gas generation, water resistance, moisture resistance, shock resistance, lightweight, low cost, and thin thickness.
Significance of Aerogel Insulation Materials:
When applied in lithium-ion power battery modules, the low thermal conductivity of aerogel insulation pads effectively blocks the rapid diffusion of heat generated during high-rate charging and discharging. In the event of thermal runaway, the aerogel insulation pads provide thermal insulation, delaying or preventing accidents. If the battery cells become overheated and catch fire, the aerogel insulation pads, with their non-combustible properties (complying with A1 level requirements), can effectively block or delay the spread of fire. This ensures that the battery pack remains non-flammable and non-explosive for at least 5 minutes, providing sufficient time for evacuation. Thus, aerogel insulation pads play a vital role in enhancing the safety performance of new energy vehicle power battery packs.
Conclusion:
Although aerogel insulation materials come at a higher price, their superior safety performance outweighs that of other traditional insulation materials. They are recognized as the best choice for power battery insulation and flame retardant materials. As the importance of safety in new energy vehicles continues to grow, the application of aerogel insulation materials, particularly in electric buses and high-end new energy cars that have higher safety requirements, is undoubtedly the optimal choice. According to experts' estimations, the global sales of new energy vehicles are expected to account for one-third of total vehicle sales by 2025. This indicates a promising future for aerogels. As the production scale of aerogel materials matures and expands, prices are expected to decrease, resulting in increased market penetration and application in the new energy vehicle industry.
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